What caused this strange code-like pattern to form on an Icelandic lake?

The real message might be a warning about climate change.

Residents living around Iceland's Lake Thingvallavatn were recently mystified after waking up and discovering a strange, code-like pattern sketched across the ice-covered lake like some kind of mysterious hieroglyph. The pattern emerges from a split in the ice, but with its sharp right angles, it doesn't look like a natural split.

Officials with Thingvellir National Park posted images of the strange formations to the park's Facebook page, noting that a pattern like this has never been seen before on the lake, and that it remains unexplained. Some other angles of the unusual phenomenon can be viewed here:

A different angle of Lake Thingvallavatn. (Photo: Thingvellir National Park/Facebook)

Is it an alien barcode? Some kind of Icelandic version of crop circles? Is there a message in the pattern that can be deciphered?

Though the pattern looks eerily unnatural, as if written by an intelligent designer, it's probably nothing too spooky. In fact, the design looks suspiciously like a natural phenomenon known as "finger rafting," which can happen when two expanses of sheet ice converge toward another, and one of them slides smoothly on top of the other, as illustrated by this diagram:

How finger rafting works. (Photo: Wiki Commons)

Finger rafting hasn't been confirmed as the cause of the strange pattern yet, and the conditions present on the lake aren't usually conducive to generating this phenomenon, but it's still the leading theory about what's going on here, according to Ice News.

Even if finger rafting is the explanation, however, there's still the question of why this is happening now, when it has never happened on this lake before. Officials offer a hint of an answer on the Facebook page:

"Lake Thingvallavatn used to have solid ice cover from around early January until spring. For the last 15 years solid ice cover on the lake has not formed as solid as in the past due to increasing temperatures. The lake has gathered partial ice cover for shorter periods and more unstable."

In other words, perhaps there's a message hidden in the pattern after all, and that message is a reminder about our changing climate. A pattern like this has never been seen before on Lake Thingvallavatn, but perhaps that's because the environmental conditions around the lake this year are a deviation from the norm.

It goes to show that even natural phenomenon can have unnatural causes — or even stories to tell.